In some types of corrective surgery for eyes it becomes necessary to transplant corneal tissue from a donor to a recipient. In performing this transplant operation a corneal trephine is used. A corneal trephine is a surgical instrument used to cut a circular section or button from the corneal tissue. In performing the transplant operation a trephine is used to remove a button or cylindrical portion of transplant tissue from the donor's cornea and is used to form an opening in the recipient's cornea into which the transplant tissue is placed.
It is of critical importance to cut the opening in the recipient's eye as close as possible to the same size and shape as the button cut from the donor's eye. It has been found that the cornea is an elastic structure and that shear deformities can occur during the cutting process which distort the shape of the corneal button and cause discrepancies between the donor and recipient cuts.
In performing corneal grafting operations, an undistorted and unobstructed view of the cutting is important. Surgeons now use operating microscopes to view the graft to obtain a better view of the cutting steps.
Corneal trephines which are currently available either do not provide a full view of the cutting operation or tend to cause distortions in the cutting operation.